Construction of Nitrogen‐abundant Graphyne Scaffolds via Mechanochemistry‐Promoted Cross‐Linking of Aromatic Nitriles with Carbide Toward Enhanced Energy Storage

Abstract

The 2D graphyne‐related scaffolds linked by carbon–carbon triple bonds have demonstrated promising applications in the field of catalysis and energy storage due to their unique features including high conductivity, permanent porosity, and electron‐rich properties. However, the construction of related scaffolds is still mainly limited to the cross‐linking of CaC2 with multiple substituted aromatic halogens and there is still a lack of efficient methodology capable of introducing high‐concentration heteroatoms within the architectures. The development of alternative and facile synthesis procedures to afford nitrogen‐abundant graphyne materials is highly desirable yet challenging in the field of energy storage, particularly via the facile mechanochemical procedure under neat and ambient conditions. Herein, graphyne materials with abundant nitrogen‐containing species (nitrogen content of 6.9–29.3 wt.%), tunable surface areas (43–865 m2 g−1), and hierarchical porosity are produced via the mechanochemistry‐driven pathway by deploying highly electron‐deficient multiple substituted aromatic nitriles as the precursors, which can undergo cross‐linking reaction with CaC2 to afford the desired nitrogen‐doped graphyne scaffolds efficiently. Unique structural features of the as‐synthesized materials contributed to promising performance in supercapacitor‐related applications, delivering high capacitance of 254.5 F g−1 at 5 mV s−1, attractive rate performance, and good long‐term stability.

Homocoupling of Fluoroarenes: A Mechanochemical Approach Toward Porous Conjugated Scaffolds Construction

“…The specific capacitances based on the GCD curves (Figure 4C) were calculated to be 121.1 F g −1 at 0.2 A g −1 and maintained at 66.7 F g −1 at 10 A g −1 . Moreover, the symmetric supercapacitor exhibited commendable energy densities of 13.6 and 7.5 Wh kg −1 at power densities of 90 and 4500 W kg −1 (Figure 4D), which is comparable to previously reported carbon materials with high surface areas in the same electrolyte, such as aza-fused graphyne materials (10 Wh kg −1 at 90 W kg −1 ), 30 phosphorus-doped cubic ordered mesoporous carbon (10.01 Wh kg −1 at 0.3 kW kg −1 ), etc. 55 Moreover, it outperforms other organic conjugated polymers even those with abundant redox sites, such as ketoenamine-linked covalent organic frameworks (∼40 F g −1 at 0.1 A g −1 in 1 M H 2 SO 4 ), etc.…”

“…Notably, the integration of micropores (1 nm) and mesopores is extremely beneficial for the supercapacitor application, in which the ultramicropores could boost the charge storage thus enhancing the supercapacitance and the mesopores could fasten ion mobility thus enhancing the rate performance. 30,48 The Raman spectra (Figure 2H) of F 4 (CN) 2 -CPN-1.0′ reveals two diffraction peaks: the intensive D-peak at 1345 cm −1 from the sp 2 breathing vibration of the aromatic carbons, which represents the lattice defect of sp 2 carbon, and the G-band at 1587 cm −1 , which is the in-phase stretching vibrations of sp 2 carbon. 49 The ratio of I D /I G was 1.46 according to the Voigt fitting, which indicated abundant defect sites within the scaffolds.…”

“…Generally, the current density (i) is determined by the scan rate (ν) according to the equation i = a*ν b , where b values of 1, 0.5, and between 0.5 and 1 region correspond to ideal capacitive behavior, diffusioncontrolled kinetics, and a combination of diffusion and capacitive processes, respectively. 30 To determine the b value, the logarithm of absolute current densities can be plotted against the logarithm of scan rates using the equation (log i = a + b logν). As shown in Figure 3B, the b values of F 4 (CN) 2 -CPN-0.5, F 4 (CN) 2 -CPN-0.5′, and F 4 (CN) 2 -CPN-0.5″ were 0.961, 0.910, and 0.675, respectively.…”

“…For example, N doping has been demonstrated to induce the extra pseudocapacitance by the faradic redox reaction between the N species and the electrolyte. 30,33 In addition, B doping was a promising strategy to boost electrochemical oxygen evolution reactions due to the lower electronegativity of B sites and their positively charged nature, which facilitates the effective chemisorption of negatively charged oxygen atoms. 34,35 Therefore, it is highly attractive but still challenging to introduce extra heteroatoms within the nanoporous fluorinated CPNs to deliver a good performance.…”

Green synthesis of oxygenic graphyne with high electrochemical performance from efficient mechanochemical degradation of hazardous decabromodiphenyl ether

“…4f) reveals its well-ordered structure with certain defects, as evidenced by the G-band around 1573 cm −1 and the D-band around 1344 cm −1 , which may be ascribed to the aromatic C–C bond stretching and defects, respectively. 30 Moreover, the lower intensity ratio of D and G bands ( I D / I G = 0.56) indicates the high regularity of the internal structure, which is beneficial for its application in electrochemical field.…”